RF modules are widely used in electronic design owing to the difficulty of designing radio circuitry. Good electronic radio design is notoriously complex because of the sensitivity of radio circuits and the accuracy of components and layouts required to achieve operation on a specific frequency.

The Digital Light Dependent Resistor LDR Sensor Module is used to detect the presence of light / measuring the intensity of light. The output of the LDR module goes high in the presence of light and it becomes low in the absence of light. You can adjust the threshold (sensitivity) of the digital output by tuning the onboard variable resistor (potentiometer). Simple usage as it is the digital output, so you will know is the light present and decide what to do with it.LDR photoresistor sensor module comes with an M3 mounting hole for ease of attaching it to an object. Onboard, it provides an LDR, high sensitivity and commonly being used for light detection.

This Arduino touch sensor module based on the dedicated TTP223 touch sensor IC. The TTP223 capacitive touch switch provides a single integrated touch sensing area of 11 x 10.5mm with a sensor range of ~5mm. An on-board LED will give a visual indication of when the sensor is triggered. When triggered the module's output will switch from its idle low state to high (default operation). Solder jumpers allow for reconfiguring its mode of operation to be either active low or toggle output.